function Animal() {}
Animal.prototype.species = '动物'

function Cat(name, color) {
    this.name = name;
    this.color = color;
}

function extend(Child, Parent) {
    var F = function() {}; // 空函数对象， 内存开销不大
    F.prototype = Parent.prototype;
    Child.prototype = new F();
    Child.prototype.Constructor = Child;
    Child.uber = Parent.prototype;
}

extend(Cat, Animal);
var cat1 = new Cat('小花', '白色');
console.log(Animal.prototype.constructor);
console.log(cat1.species);